Writing in Food Chemistry, researchers noted that current methods used to obtain the colourant “have several drawbacks, such as involving much time, hard work, low selectivity and low extraction efficiency.” In addition they noted that current conventional techniques use large amounts of toxic solvents.
To try and solve some of these issues, the researchers – from the University of La Laguna, Spain – tested various extraction solvents and techniques to remove carminic acid from cochineal samples. They then drew up optimum extraction conditions – finding that pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE) showed good potential as removal techniques.
“These new methods have been developed with the intention of reducing the allergenic protein content in this dye originating from the insects themselves,” said the researchers – led by Emma Borges, of La Laguna.
In addition, Bourges and her team studied the stability of carminic acid extracted, and the possibility of using different techniques to alter the colour of acid produced.
“Several lakes were prepared from carminic acid extracted and the possibility of replacing salt with the less polluting alumina was studied to obtain different lake colours,” they said.
Carmine is a water insoluble colour dye used in a wide variety of food products including juices, ice cream, yogurt, and confectionery. Although principally a red dye, it is often used in the production of foods that are hues of red, pink, and purple.
The colourant is made from carminic acid, produced from the ground bodies of cochineal insects (Dactylopius coccus) – primarily found and grown in South America. However, the soaring price of cochineal, in addition to calls for alternative natural colours from non animal sources has led manufacturers to begin the search for carmine alternatives – such as beetroot –in recent times.
By reducing the cost and complexity of carminic acid extraction, the researchers believe the optimised extractions could help to make carmine more attractive to industry again.
They noted in particular that SFE, using carbon dioxide as solvent, “has gained much attention for fast and effective extraction of a wide variety of dye and food compounds … due to the fact that is an environmentally benign solvent.”
They said that the technique works under mild extraction conditions, so avoiding degradation of biological products, whilst noting that its solvating power is easily manipulated by changes in pressure and temperature.
Borges and her colleagues said that the optimised extraction techniques suggested produced improved carminic acid and carmine lakes – and could help to make extraction of the dye more economical and sustainable by reducing the need for industrial solvents. They added that improved extraction methods may help to reduce the protein content in dyes, so reducing the allergenic potential of the dye.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2011.12.018
“Natural dyes extraction from cochineal (Dactylopius coccus). New extraction methods”
Authors: M.E. Borges, R.L. Tejera, L. Díaz, P. Esparza, E. Ibánez